Scandium, yttrium and lutetium
The first two metals formally belong to the set of transition metals. This is because of the way, the electron shells are filled when going from left to right in the periodic table of the elements. Going from group 2 (the earth alkali metals) to group 3, a d-electron is added to the neutral atom, instead of a p-electron.
On this site, lutetium is placed under yttrium in the periodic table chart. This suggests it is a transition metal, similar to yttrium. Chemically speaking this indeed is the case. There is some dispute, however, about which of lanthanum or lutetium must be regarded a transition metal and which must be regarded a lanthanoid. An equally plausible periodic table chart can be given, with lanthanum as transition metal under yttrium, and lutetium being the last lanthanoid. The chemical properties of lutetium and lanthanum are very similar.
Chemically speaking, these three metals hardly have the interesting properties of the other transition metals in their row. They display the gradation in properties that might be expected from elements immediately following the earth alkali metals. They are quite electropositive and slowly attack water, with the evolution of hydrogen.
In their compounds these metals only exist in the +3 oxidation state. This is in marked contrast to most of the other transition metals, which can exist in multiple oxidation states. The trivalent ion of these metals is colorless. These metals still are really basic, they do not form anionic species in alkaline environments, like aluminium does. On addition of a strongly alkaline solution to a solution of a salt of one of these metals the basic hydroxide precipitates, which does not dissolve on addition of more alkaline solution.
Sometimes, samples of these metals can be purchased on eBay. These samples are quite expensive. The metals, although they have some interesting properties, such as being strong reductors, do not add much to a home lab, when their price is taken into consideration. The compounds of the metals with their trivalent colorless ions are not really interesting for the home chemist. They have no extensive redox chemistry in water and only limited coordination chemistry. Most complexes are colorless as well, so without special equipment, nothing interesting can be detected on these complexes.